[SpartaEvolution]

If you were rattle canning them in your backyard that'd probably be fine, but if you're going to pay to have the calipers professionally powder coated, you may as well do it right. If you don't disassemble the halves, you'll have to PC the head of the bolts making them harder to remove should you ever need to disassemble the caliper, and doing so would ruin the PC around the bolt holes anyways. Leaving them assembled will also likely lead to bubbling between the two halves as the PC will try to adhere to both sides.